David Robson: Green season brings attention back to the lawn

Friday

Mar 26, 2010 at 12:01 AMMar 26, 2010 at 12:12 PM

Daffodils are blooming. Magnolias are plumping. Red and silver maples are in full bloom (though you can see just the hint of color around the plants). Forsythia is this close to blooming. It means spring is here — not just officially, but in reality. Spring also means the grass is greening, and that means the start of lawn care.

David Robson

Daffodils are blooming. Magnolias are plumping. Red and silver maples are in full bloom (though you can see just the hint of color around the plants). Forsythia is this close to blooming.

It means spring is here — not just officially, but in reality.

Spring also means the grass is greening, and that means the start of lawn care.

Fall is a much better time to concentrate on lawn care, especially with cool-season grasses such as bluegrass, fescues and ryegrass. Zoysia, one warm-season grass, is still dormant and won’t start greening for another few weeks.

We look to fall as the best time to seed, aerate, dethatch and fertilize because the grass has more than half a year to recover before the dreadful heat of summer.

Spring activity gives grass two to three months of ideal growing conditions before summer hits hard. Having a healthy, extensive and deep root system is the best guard to making sure grass survives.

The first thing most homeowners will do is fire up the lawn mower, hopefully after making sure the blade is sharp. A good lawn mower tuneup is worth the cost, especially if they clean the air filter and spark plug and make sure the oil is changed.

But a sharp, clean blade is the most essential, especially if you want a professional-looking lawn instead of one that looks ragged and jagged.

If your mower is coughing and not running properly, either change the spark plug or take a piece of emery cloth to the contact. You’d be surprised how often a new spark plug or fresh contact is all that’s needed to get the mower puttering again.

The University of Illinois recommends that mowers be kept at the same height throughout the year. We don’t encourage folks to keep changing the mower height, unless you allow the grass to get as tall as a hayfield.

Keep the mower height between 2 and 2½ inches. Mow the lawn when the grass reaches 3 to 4 inches.

The only exception to this rule could be the first mowing of the season, when you might want to mow the turf a tad bit shorter to remove most of winter’s browning of the blades. However, it’s only the first mowing. Subsequent mowings should all be at the same height.

Walk through the yard before mowing and pick up sticks, rocks and other debris that might have accumulated during winter. This prevents mower blade damage.

The other key lawn chore at this time of the year is control of crabgrass and other spring germinating weed seeds.

Crabgrass can start germinating once the ground reaches 55 degrees for seven to 10 consecutive days. Because the seed is close to the soil temperature, the warmup can occur quickly. However, the ground can also cool quickly if we have some cool days.

Crabgrass also needs light and moisture to germinate.

Most crabgrass germinates sometime in April, or May if conditions are not favorable.

Our only good bet for control is a pre-emergent herbicide to kill the crabgrass and other weed seeds as they germinate. To work, the chemical has to be on the lawn before the seed sprouts.

There are many products on the market. The biggest problem with most of them is they’ll kill not only germinating crabgrass and other weed seeds, but also so-called good seeds. In other words, with most of the products, you won’t be able to seed desirable grasses at the same time
you’d control the germinating weeds.

(There is a product containing siduron, often sold as Tupersan, that provides better-than-average control of weed seedlings without affecting too many desirable grass seedlings. Expect to pay more.)

If your turf is dense and thick with no bare spots, you probably won’t have a problem with crabgrass. However, if the lawn is thinned or has died somewhat during the winter, you may have a problem.

Finding just the right crabgrass killers may be difficult, but it’s worth the extra effort. The ideal crabgrass control won’t contain fertilizer, as the nitrogen will stimulate top growth at the expense of root growth when it might be more practical to have a more extensive root system going into summer.

Most crabgrass killers require some moisture to activate, so either drag out your garden hose or keep your fingers crossed that we’ll have our normal spring rains.

David Robson is a horticulture educator for the University of Illinois Extension. For more gardening information or for your local extension unit office, go to www.extension.uiuc.edu/mg.